If you want a guaranteed nectar source all year-round, plant lavender shrubs.
Here is a honey bee feeding on nectar from one of our lavender shrubs in the front yard during a break between winter rainstorms.
Note the orange pollen on its leg.
Our lavender shrubs aren't very big, but as long I keep pruning dead branches and deadhead the spent flowers, the shrubs keep producing new flowers.
The winter rains work wonders on these plants.
There is so much new growth on them, and they look very refreshed.
Bees visit the lavender throughout the day whenever the temperatures are at least in the 60's and it is dry. Hummingbirds sip nectar here as well.
And in the summertime butterflies often visit, too.